(1) Field of the Invention
The present invention relates to the lubrication of movable members located in an inaccessible location and particularly to the intermittent delivery of a lubricant to a bearing surface located within a shaft furnace. More specifically, this invention relates to lubrication devices for incorporation in the drive and support mechanism for a charge distribution chute which is mounted within a blast furnace. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
(2) Description of the Prior Art
While not limited thereto in its utility, the present invention is particularly well suited for association with the driving and mounting mechanism for a charge distribution chute which is suspended in the throat area of a blast furnace. In a typical case, the distribution chute is mounted from a rotatable casing which is positioned concentrically around a central feed spout. Means in the form of a first mechanical drive train imparts rotary motion to the casing, to thereby rotate the distribution chute, and a further drive train rotates with the casing and drives the chute so as to vary the angular orientation thereof with respect to the furnace vertical axis. Independent drive motors are associated with each of the drive trains. The charge distribution chute is affixed, at opposite sides and adjacent the upper or charge receiving end thereof, to a pair of horizontally oriented and axially aligned rotatable shafts in such a manner that the chute will move with these shafts. The shafts may be caused to rotate about their axis through the use of a pair of reduction gear boxes which form part of the drive train which causes the variations in distribution chute angular orientation; the gear boxes rotating with the casing.
A distribution chute drive and support mechanism of the type briefly described above is disclosed in U.S. Pat. No. 3,880,302. As shown in U.S. Pat. No. 3,880,302, the horizontal shafts to which the distribution chute is affixed pass through packings and bushings in the side walls of the reduction gear boxes. Sector gears are attached to the chute supporting shafts and rotary motion is imparted to the shafts by means of driving these sector gears. As the horizontal shafts pivot about their longitudinal axis, during the adjustment of the angular position of the distribution chute, the bearing surfaces and members, for example blocks and roller bearings, on which the shafts are supported in the walls of the reduction gear boxes must be systematically lubricated.
Access to the packings and bushings about the distribution chute supporting shafts is exceedingly difficult because of the harsh operating environment and since the shafts not only rotate about their common horizontal axis but also rotate with their respective reduction gear boxes about the longitudinal axis of the furnace central feed spout. Thus, the employment of lubrication pumps including electric drive motors is impractical both as a result of the high temperature and pressure of the operating environment and also as a result of the fact that the shafts rotate about two transverse axes which renders the delivery of electrical power to a pump exceedingly difficult. Similarly, direct feed by flexible lubricating tubes or rotating connection has been found to be impractical in part because of the large diameter of the path about which the shafts rotate during rotation of the casing.
In the prior art, lubrication of the bearing blocks and roller bearings on which the rotatable support shafts for a steerable charge distribution chute of a shaft furnace are mounted has been achieved through the provision of an oil or grease chamber which rotates together with the reduction gear boxes about the central feed spout of the furnace. For such oil or grease chambers to function adequately, a sufficient level of lubricant has to be maintained therein to insure that there will be lubricant outflow, through pipes under the effect of gravity, to the components to be lubricated. While the provision of such oil or grease chambers has had some limited success, a serious hermeticity problem is presented. Due to the high operating temperatures encountered, the oil or grease becomes extremely fluid so that it is very difficult to insure hermeticity. Even if the oil or grease level is checked each time the furnace is shut-down, there is an inherent risk of leakage and loss of lubricant during operation and, should this occur, the bushings and/or bearings will seize thus resulting in their destruction followed by a lengthy and expensive shutdown of the furnace for repair purposes.